SparkFun Inventor's Kit for MicroView

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Contributors: Joel_E_B
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Experiment 6: Temperature Sensor

A temperature sensor is exactly what it sounds like – a sensor used to measure ambient temperature. This particular sensor has three pins – a positive, a ground, and a signal. This is a linear temperature sensor. A change in temperature of one degree centigrade is equal to a change of 10 millivolts at the sensor output. The TMP36 sensor has a nominal 750 mV at 25°C (about room temperature). In this circuit, you’ll learn how to integrate the temperature sensor with your MicroView, and use the serial monitor to display the temperature.

Heads up! When you’re building the circuit be careful not to mix up the transistor and the temperature sensor, they’re almost identical. Look for “TMP” on the body of the temperature sensor.

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Parts Needed

You will need the following parts:

  • 1x TMP36 Temperature Sensor
  • 2x Jumper Wire

Breadboard Setup

Hook up your circuit as pictured below:

Be sure to insert the TMP36 in the correct orientation. It is polarized and will not work if inserted incorrectly.

Circuit06_a

Once you are sure orientation is correct, you can place the remaining jumper wires.

Circuit06_b

MicroView Arduino Code

language:c
#include <MicroView.h>      // include MicroView library

MicroViewWidget *widget;    // declare widget pointer

int sensorPin = A0;     // select the input pin for the temperature sensor
int sensorValue = 0;    // variable to store the value coming from the sensor

void setup() {
    pinMode(sensorPin,INPUT);   // set sensor pin as INPUT
    uView.begin();              // start MicroView
    uView.clear(PAGE);          // clear page
    widget = new MicroViewGauge(32,24,0,255,WIDGETSTYLE1);      // declare as gauge widget
    uView.drawChar(47,33,67);   // Character C is ASCII code 67
}

void loop() {
    sensorValue= analogRead(sensorPin);             // read sensor pin value
    float voltage = sensorValue * 5.0;              // voltage at pin in volt
    voltage /= 1024.0;                              // voltage = sensorValue x (5/1024)
    float temperatureC = (voltage - 0.5) * 100 ;    // C = (voltage - 0.5) x 100
    widget->setValue(temperatureC);                 // set temperature value to the gauge
    uView.display();                                // display gauge tick
}

What You Should See

As you warm and cool your temperature sensor, you should be able to see the gauge on your MicroView’s display go up or down.

Troubleshooting

Temperature Value is Unchanging

Try pinching the sensor with your fingers to heat it up or pressing a bag of ice against it to cool it down.

Still No Success?

A broken circuit is no fun, send us an e-mail and we will get back to you as soon as we can: TechSupport@sparkfun.com